Underlying Principles

Three generalisations can be extracted from the past century of observations on fruiting physiology. First, the organism internalises nutrients rapidly to gain regulatory control over nutrient access and distribution. By so doing the vegetative mycelium becomes competent to produce multicellular structures like fruit bodies. Second, factors that promote fruiting, whether physical or chemical, seem to work by disturbing the normal progress of cellular metabolism. It is the disturbance itself that is the effective factor, overcoming some block to progress and inducing the next stage to proceed. Consequently, parallel pathways cover some stages of fruit body development and for these stages different factors seem to be interchangeable (e.g. a particular nutritional state may replace a particular illumination requirement). Third, even relatively simple developmental pathways can be subdivided into stages (at least, initiation, development and maturation) and there seems to be a need for successive signals (successive metabolic disturbances) to maintain progress of the developmental process. Each stage involves change in hyphal behaviour and physiology, taking the tissue to a higher order of differentiation.

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